1. Field of the Invention
The present invention relates generally to recliners for vehicle seats and, more particularly, to a recliner which is mounted to a vehicle seat to function as a hinge for rotatably coupling a seat back to a seat cushion and enabling the angle of the seat back relative to the seat cushion to be adjusted to and stay fixed at the adjusted angle, thus providing the optimal seating posture to a user, and which is strong enough to protect the user when a vehicle collision occurs.
2. Description of the Related Art
Hereinafter, a representative example of the related art and problems thereof will be explained in detail with reference to the drawing.
FIG. 1 is a view showing the construction of a conventional recliner for vehicle seats.
Referring to FIG. 1, the conventional recliner 1 includes a gear rim 10, a guide plate 14, a cam 12 and locking gears 13. The gear rim 10 has a receiving depression (not shown) in a first surface thereof. Internal gear teeth 102 are formed in the rim part of the receiving depression. The guide plate 14 is attached to the first surface of the gear rim 10. A plurality of guide blocks 142 protrude from a second surface of the guide plate 14. The two facing guide blocks 142 define a locking gear guide depression 141. The cam 12 is interposed between the guide plate 14 and the gear rim 10 and is fitted at the center thereof over a lever rotating shaft 2. Each locking gear 13 is inserted into the corresponding locking gear guide depression 141. External gear teeth 131 are formed in the circumferential outer surface of each locking gear 13.
In the conventional recliner 1 having the above-mentioned construction, when the lever rotating shaft 2 rotates in a clockwise direction, both ends of the cam 12 which rotates along with the lever rotating shaft 2 push the diametrically opposed inner surfaces of the locking gears 13 towards the outside of the guide plate 14. Thereby, the locking gears 13 move along the corresponding locking gear guide depressions 141, so that the external gear teeth 131 of the locking gears 13 engage with the internal gear teeth 102 of the gear rim 10, thus entering the locked state.
However, in the conventional recliner 1, because of the structural characteristics in that each locking gear 13 slides along the corresponding locking gear guide depression 141, fine gaps for ensuring the movement of the locking gear 13 are formed between both sidewalls of the locking gear 13 and the inner surfaces of the corresponding guide blocks 142 which define the locking gear guide depression 141 therebetween. Furthermore, because the locking gear 13 repeatedly slides along the locking gear guide depression 141, abrasion is induced on both sidewalls of the locking gear 13 and the inner surfaces of the guide blocks 142 because of friction therebetween. Therefore, as the number of times the recliner is used increases, gaps between the locking gear 13 and the guide blocks 142 is gradually increased, with the result that the seat back undesirably moves around the rotating shaft, thus causing inconvenience to the user.
Moreover, when external force is applied to the recliner 1, a force applied to each locking gear 13 by the external force is focused on the sidewall of one of the guide blocks 142 that are disposed on both sides of the locking gear 13. Thereby, the locking gears 13 or the guide blocks 142 are easily deformed. In the case where the locking gears 13 or the guide blocks 142 are deformed, clearance between the locking gears 13 and the guide blocks 142 is increased. Thus, the seat back moves at an undesirably large angle around the rotating shaft.
In addition, when the recliner is in the locked state, only small areas of the cam 12 are in contact with and supporting the locking gear 13. Stress is focused on the cam 12, with the result that the cam 12 is easily deformed or damaged.